Devices for adjusting the upper edge of a lower work roll to a roll line are known. For example, it is known to adjust the upper edge of the work rolls to the rolling line by the use of adaptor plates of varying heights. These adaptor plates, which are moved in and out by a carriage together with the roll chocks, are selected in accordance with the amount of height adjustment that is necessary in each particular case. However, this solution is not particularly advantageous, since two special adaptor plates are required for each height adjustment with the adaptor plates for large height adjustments being difficult to handle.
From Federal Republic of Germany Patent No. 28 06 525 A1, a device is known for selectively introducing fitting pieces of different height included in a removing frame below the roll chocks into the housing openings of a four-high stand for adjusting the upper edge of the work roll. For this purpose, traverse cylinders are arranged in the housings in order to lift the roll chocks so that the appropriate height fitting piece segment may be positioned underneath the roll chock. However, these cylinders necessitate expensive machining of the housings.
European Patent No. 02 31 445 discloses a device for the vertical displacement of rolls in a roll stand having fitting pieces of different height and a pair of wedges arranged below each roll chock of the back-up roll. Accordingly, by use of the pair of wedges, the height of the roll can be continuously adjusted with the lower wedge being displaceable in a horizontal direction and the upper wedge being displaceable in a vertical direction. In this prior art reference, one of several differing height fitting pieces is inserted between the upper wedge and the bottom of the chock of the roll. These fitting pieces are moved into the working position, one after the other by transverse displacement. In this way, as described in this reference, a stepwise compensation of the position of the work roll can be effected by the insertion of one of the differing height fitting pieces, with the wedges serving to bridge the differences in height between steps.
As a result of the arrangement of the displaceable fitting pieces and wedges alongside each other, this device is very expensive to construct. Furthermore, the arrangement of this device requires sufficient space in order to provide for the insertion of the different stepped fitting pieces under the work roll.
In order to overcome the disadvantages of the prior art, and in particular European Patent No. 02 31 445, the object of the present invention is to simplify this device in order to provide a simple, space-saving arrangement, so that the upper edge of the lower work roll can be precisely positioned to the rolling line.
In order to achieve this object and in accordance with the invention, each upper wedge element is adapted to be raised and lowered by a lift device together with the corresponding roll chock. Additionally, the wedge surfaces of both corresponding wedges are ratcheted or stepped with the ratchets or steps engaging each other so that the wedge elements are vertically supporting.
One aspect of the present invention resides in connecting the upper wedge element itself, on the one hand, with the lift element for the chock of the roll to be lifted and, on the other hand, simultaneously utilizing the wedge element for supporting the chock in the desired vertical position. By lifting the upper wedge element itself and the roll chock away from the lower wedge element, it is possible to shift the lower wedge element into the position desired in each case and then lower the upper wedge element and roll chock onto it. In order for the wedges to self-lock, the wedge surfaces are constructed in a stepped or ratcheted shape. In this way, the wedges can be made very short, as a result of which the path of displacement can be kept extremely short. Thus, an extremely simple, as well as strong, device is created which can be arranged in a small space within the roll stand.
In accordance with another feature of the present invention, the upper wedge element is part of a cross member which extends over the lower wedge element. The cross member, which is preferably I-shaped, can then be raised and lowered by piston-cylinder units arranged laterally along the lower wedge element. Accordingly, the corresponding upper wedge element and the cross member are guided in a vertical direction to a position above the desired height. The use of such a cross member permits the use of a piston-cylinder lift device positioned outside of the path of displacement of the lower wedge elements. These piston-cylinder units can, for instance, be flanged onto the side of the roll housings. In addition, the piston-cylinder units are readily visible for inspection. Additionally, the corresponding roll chock rests on the cross members, on the lower side of which the upper wedge element is provided.
In accordance with another feature of the present invention, the guide for the cross member consist of at least two guide bolts which are surrounded by corresponding vertical holes in the cross member.
These guides ensure that the upper wedge element is freely movable solely in the vertical direction. The guide bolts and corresponding holes are simple structural elements which fully satisfy the requirements present here.
Additionally, it has been found that favorable support conditions are obtained if the ratio of the horizontal length to the vertical length of the steps ranges from about 2:1 to about 3:1. Moreover, the height and number of the steps are selected in accordance with the requirements of the displaceability of the work rolls, with the rule that, generally, a finer adaptation to the vertical position can be effected with a plurality of small steps rather than with only a few high steps.